Sacramento -- After seven years in the making, the $25 billion plan to build two massive tunnels diverting water out of the Sacramento-San Joaquin River Delta is up for public review. And one thing is clear: You better grab your reading glasses.

The 9,000-page Bay Delta Conservation Plan and 25,000-page environmental impact report pack a hefty punch, particularly considering the public has 120 days to comment on the documents, which state officials said contain significant revisions since first drafts were released this year.

Accompanying executive summaries and brochures on the Bay Delta Conservation Plan's website say the proposal, which has the backing of Gov. Jerry Brown, is an important step in the effort to restore the delta ecosystem and stabilize the water supply for 25 million Californians and 3 million acres of farmland from San Jose to San Diego.

"This is a rational, balanced plan to help meet the needs of all Californians for generations to come," said California Natural Resources Secretary John Laird in a statement.

The public-comment period begins Friday and ends April 14. Once it ends, the state can revise its plan before submitting it to state and federal wildlife agencies, which will decide whether to issue the necessary permits to move forward.

"The delta matters to the entire state," said Nancy Vogel, spokeswoman for the Department of Water Resources. "For a generation, Californians have been debating in courts and courts of public opinion on how we can have a rich estuary in the delta and also divert the water 25 million people and 3 million acres of farmland depend on. We are trying to modernize our water system in a way that protects the environment."

However, the delta diversion plan continues to draw fire from environmental groups and some lawmakers. Critics have characterized the tunnels as nothing more than a water grab they liken to the peripheral canal plan that California voters rejected in 1982.

"I continue to be concerned that the state has chosen to follow a path that will not solve either the state's water supply or the delta's ecosystem challenges," said state Sen. Lois Wolk, D-Davis, whose district includes much of the delta.

Jeffrey Michael, an economist at the University of the Pacific in Stockton, said the $25 billion project estimate isn't a complete picture because it doesn't include financing costs. The delta tunnels will need $1.2 billion for planning costs prior to construction and the state water department said those costs are included in the $25 billion price tag. To date, the water districts that buy water pumped from the Delta have committed $240 million to the project.

State and federal water contractors - which provide water to millions of Californians and to farms - would contribute about 68 percent of the total funding, while state and federal funds account for the rest. The state, which anticipates sharing $4.1 billion of the cost, is banking on the 2014 water bond on the statewide ballot for its initial share and subsequent bonds for future habitat restoration funds. Wolk, who opposes the tunnels, is carrying one of two water bond proposals in the Legislature.

"This will all be paid for on the backs of California rate payers," said Barbara Barrigan-Parrilla, executive director of Restore the Delta. "In terms of the San Francisco Bay, this will have a negative impact on the bay that no one has analyzed. The bay is dependent on fresh-water feed, and if that water is diverted, it will have an environmental impact."

This story has been updated since it appeared in print editions.

Delta tunnels

To see the Bay Delta Conservation Plan and the accompanying environmental impact report on the plan to build two tunnels under the delta, go to: http://bit.ly/IMKGli.